Lineup modifications continue in attempt to manufacture runs

Jason Castro will try his luck in the third spot in the Astros' batting order. ( Smiley N. Pool / Houston Chronicle )

With the Astros entering Tuesday’s late game against the Mariners having been shut out three times in seven contests, first-year manager Bo Porter continued to fine-tune his lineup in an effort to create a much-needed spark.

Catcher Jason Castro was bumped up to the No. 3 position, while center fielder Justin Maxwell remained in the two hole. The lineup gave the Astros their top two hitters at the front of the lineup — leadoff batter Jose Altuve and Maxwell — and placed Castro, who the team believes is on the verge of a breakout, ahead of free-swinging power hitters Chris Carter and Carlos Pena.

“As we go through this early stage of the season … we’re just trying to find the right combination and get guys into slots where they’re going to be productive,” Porter said.

GM preaches patience at plate

The Astros have slightly adjusted their hitting approach since the regular season started, but the club hasn’t made any wholesale changes.

While some hitters have been too aggressive and others have expanded their strike zone as pressure has mounted, general manager Jeff Luhnow said it’s too early to make any drastic alterations.

“It’s tempting to make changes right out of the gate, especially when you’re not having success. But we have to be patient,” Luhnow said.

The Astros entered Tuesday with 82 strikeouts and only two walks and two home runs. The club ranked 28th out of 30 teams in batting average (.201) and on-base percentage (.234) and 29th in slugging percentage (.275).

Astros starter Philip Humber made it through six innings in Monday’s 3-0 loss to the Mariners. As a result, manager Bo Porter believes his bullpen is rested after being used often and hit hard during season-opening home series against the Texas Rangers and Oakland Athletics.

The Astros have added young starters Dallas Keuchel and Paul Clemens to their bullpen. The duo can be used in long relief if an Astros starter exits early.

With the team about to face the hard-swinging Los Angeles Angels from Friday through Sunday in Anaheim, Calif., maintaining a smooth balance between the starting rotation and relievers will be crucial.

“I feel like (the bullpen) is coming back together,” Porter said. “We had a couple games there where we were a little bare.”